Spectral super-resolution has attracted research attention recently, which aims to generate hyperspectral images from RGB images. However, most of the existing spectral super-resolution algorithms work in a supervised manner, requiring pairwise data for training, which is difficult to obtain. In this paper, we propose an Unmixing Guided Unsupervised Network (UnGUN), which does not require pairwise imagery to achieve unsupervised spectral super-resolution. In addition, UnGUN utilizes arbitrary other hyperspectral imagery as the guidance image to guide the reconstruction of spectral information. The UnGUN mainly includes three branches: two unmixing branches and a reconstruction branch. Hyperspectral unmixing branch and RGB unmixing branch decompose the guidance and RGB images into corresponding endmembers and abundances respectively, from which the spectral and spatial priors are extracted. Meanwhile, the reconstruction branch integrates the above spectral-spatial priors to generate a coarse hyperspectral image and then refined it. Besides, we design a discriminator to ensure that the distribution of generated image is close to the guidance hyperspectral imagery, so that the reconstructed image follows the characteristics of a real hyperspectral image. The major contribution is that we develop an unsupervised framework based on spectral unmixing, which realizes spectral super-resolution without paired hyperspectral-RGB images. Experiments demonstrate the superiority of UnGUN when compared with some SOTA methods.

Fusion-based hyperspectral super-resolution (HSR) algorithms usually utilize a low-resolution hyperspectral image (LR-HSI) and a high-resolution multispectral image (MSI) to generate a high-resolution hyperspectral image (HR-HSI), which have attracted increasing attention in recent years. However, how to deal with the abundant spectral information of hyperspectral images and complex structure characteristics of MSIs has always been the focus and difficulty of fusion-based HSR. In this article, we propose a new structure–color preserving network (SCPNet) for HSR, which is developed under the basis of the joint attention mechanism. The SCPNet mainly includes three modules: structure-preserving module (SPM), color-preserving module (CPM), and cross-fusion module. The SPM is constructed based on the spatial attention, which aims to capture and enhance the significant structure information from the high-resolution MSI. Meanwhile, the CPM is constructed based on the channel attention, where the spectral characteristics in the LR-HSI are preserved during the reconstruction process. Finally, we propose a cross attention-based cross-fusion strategy to integrate the features from the two branches and reconstruct the final HR-HSI. The major contribution of SCPNet is that the structure and color information is described and preserved via the joint attention mechanism. Experimental results indicate that the proposed SCPNet has presented advantages on three benchmark datasets when compared with some state-of-the-art HSR methods.